[Elecraft] Question about K2 power meter

[Don Wilhelm]

David,

If your amp only requires 30 watts for full drive AND it is truly 
linear, you should be able to tune it successfully with a 5 to 10 watt 
input where the power is a bit more steady and then increase the level 
to obtain full output.  Just a suggestion.

If the variation is quite bothersome, your K2/100 may be a candidate for 
increasing the value of R98 (on the bottom of the RF Board) to slow down 
the power variation.  If you increase it too much, the power output on 
the higher bands may decrease (check that with the basic K2, not with 
the KPA100 powered).  In most cases, about 1k is the upper limit for the 
value, but if your K2 has greater gain than the average, you may find 
success with even higher values.  It is easiest to substitute a 2k pot 
for R98 when testing for the best value, then measure the pot resistance 
and put in the nearest fixed value resistor.

This procedure is listed on the Elecraft website - in Builder's 
Resources IIRC.

73,
Don W3FPR

David Douglass wrote:
> Jeff,
> 
> This variation in power out during tuning seems quite normal to me, and my
> K2(100) does exactly the same..
> 
> It never used to bother me but I recently bought a Emtron DX-1 amp, and it
> makes tuning the amp pretty tricky.. I only need about 30w to drive the amp
> to full output, but during tune up the power out from K2/100 will creep up
> and trip out the Overdrive on the amp. It would be nice to just dial up the
> required power from the K2 you wanted and get it, but I suppose I'll just
> have to live with this little quirk. I still wouldn't trade K2 for another
> radio!!
> 
> David, VK2NU
> 
> 
> 
> 
> Date: Sun, 22 Apr 2007 20:50:38 -0700
> From: "Jeff Kinzli N6GQ" <jeff at N6GQ.com>
> Subject: Re: [Elecraft] Question about K2 power meter
> To: w3fpr at arrl.net
> Cc: Elecraft Mail Posting <elecraft at mailman.qth.net>
> Message-ID:
> 	<e4a9cfd80704222050y6742049by5549aec87a327804 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> Hi Don,
> 
> Thanks for the replies.
> 
> To answer your questions, the problem occurs into a dummy load.
> 
> I set the base K2 (without KPA100 connected) to 5.0W, and then TUNE,
> and it starts at 5.0W and heads upwards to 5.7-6.0W (read from the
> display, as well as the S-meter). After about 10 seconds in TUNE, it's
> up to 5.7 or 6W and the next LED on the S-meter is starting to flicker
> some.
> 
> Moving the power knob will allow me to bring it back to 5.0W, but the
> next TUNE will see the power climb back up again.
> 
> I'm not sure if I should still be looking on the RF board at this
> point, or start focusing on the control board...?
> 
> Thanks, 73,
> 
> Jeff
> 
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